Electrical circuit, pulse radar device, method for providing an output signal, and radar method

Abstract

An electrical circuit for providing an output signal based on a first input signal and a second input signal has: a mixer which is configured to receive and mix the first and second input signals in order to generate a mixer output signal and to switch on or off based on the first input signal, wherein a DC signal component of the mixer output signal depends on whether the mixer is switched on or off; and a downstream circuit which is configured to switch on or off based on the DC signal component of the mixer output signal and to provide the output signal based on the mixer output signal.

The invention claimed is: 
     
       1. An electrical circuit, comprising:
 a mixer configured to receive and mix a first input signal and a second input signal to generate a mixer output signal and to switch on or off based on the first input signal, wherein a DC signal component of the mixer output signal depends on whether the mixer is switched on or off; and 
 a downstream circuit configured to switch on or off based on the DC signal component the mixer output signal and to provide an output signal based on the mixer output signal. 
 
     
     
       2. The electrical circuit as claimed in  claim 1 , wherein the DC signal component of the mixer output signal has a first level if the mixer is switched on and a second level if the mixer is switched off. 
     
     
       3. The electrical circuit as claimed in  claim 1 , wherein the mixer has at least one transistor, wherein the transistor is biased in such a manner that the transistor is switched off if a power of the first input signal is below an input threshold value and is switched on if the power of the first input signal is above the input threshold value, and wherein the mixer is configured to provide the DC signal component of the mixer output signal based on a DC component of a current through the transistor. 
     
     
       4. The electrical circuit as claimed in  claim 3 , wherein the mixer is configured to modulate the current through the transistor in a switched-on state based on at least the second input signal and to provide the mixer output signal based on the current through the transistor. 
     
     
       5. The electrical circuit as claimed in  claim 1 , wherein the downstream circuit has a short-time integrator which is configured to provide an integrator output signal based on the mixer output signal, wherein an amplitude of a useful signal component of the integrator output signal depends on a temporal overlap of a pulse of the first input signal and a pulse of the second input signal. 
     
     
       6. The electrical circuit as claimed in  claim 5 , wherein the short-time integrator has a low-pass filter, wherein the low-pass filter has a cut-off frequency which is higher than an inverse of a pulse duration of the first input signal and the second input signal and is lower than a signal frequency of the first input signal and the second input signal, with a result that the DC signal component of the mixer output signal remains substantially unfiltered. 
     
     
       7. The electrical circuit as claimed in  claim 5 , wherein the downstream circuit has a differential amplifier which is configured to provide the output signal based on the integrator output signal, wherein the differential amplifier is configured to switch on or off based on a DC signal component of the integrator output signal. 
     
     
       8. The electrical circuit as claimed in  claim 5 , wherein the downstream circuit has a differential amplifier which is configured to provide the output signal based on the integrator output signal, wherein the differential amplifier is configured to switch on or off based on the DC signal component of the mixer output signal. 
     
     
       9. The electrical circuit as claimed in  claim 7 , wherein the differential amplifier has at least one transistor, wherein the at least one transistor is either switched on or off depending on whether the DC signal component of the mixer output signal is below or above a mixed signal threshold value. 
     
     
       10. The electrical circuit as claimed in  claim 7 , wherein the differential amplifier is configured to hold a voltage applied to an output of the differential amplifier in a switched-off state. 
     
     
       11. The electrical circuit as claimed in  claim 9 , wherein the differential amplifier has a switching transistor arranged between a supply connection and the at least one transistor, wherein the switching transistor is configured to switch to an on or off state depending on whether the DC signal component of the mixer output signal or of the integrator output signal is below or above a mixed signal threshold value. 
     
     
       12. The electrical circuit as claimed in  claim 5 , wherein the downstream circuit has a holding capacitance which is coupled to an output of the downstream circuit for providing the output signal. 
     
     
       13. A pulse radar device, comprising:
 at least one pulse generator configured to provide a pulsed transmitter signal and a pulsed local oscillator signal based on one or more oscillator signals, wherein the pulse radar device is configured to output the pulsed transmitter signal and to receive a receiver signal which is based on an echo of the pulsed transmitter signal; and 
 an electrical circuit as claimed in  claim 1 , wherein the first input signal is based on the pulsed local oscillator signal and the second input signal is based on the receiver signal, and wherein the output signal constitutes an intermediate frequency signal of the pulsed local oscillator signal and the receiver signal. 
 
     
     
       14. The pulse radar device as claimed in  claim 13 , wherein the first input signal has a sequence of pulses, wherein a power of the first input signal is above an input threshold value during a pulse and is below the input threshold value between two pulses. 
     
     
       15. The pulse radar device as claimed in  claim 13 , wherein a pulse rate of the pulsed local oscillator signal is 10 −6 % to 10 −3 % greater or less than a pulse rate of the pulsed transmitter signal. 
     
     
       16. The pulse radar device as claimed in  claim 15 , wherein a frequency of the intermediate frequency signal is based on a difference between pulse rates of the pulsed local oscillator signal and the pulsed transmitter signal. 
     
     
       17. The pulse radar device as claimed in  claim 13 , wherein a duty factor of the first input signal is less than 5%. 
     
     
       18. The pulse radar device as claimed in  claim 13 , wherein the pulse radar device is configured to obtain, based on the intermediate frequency signal, an item of information relating to a period between an outputting of a pulse of the pulsed transmitter signal and a reception of an echo of the pulse as a receiver signal. 
     
     
       19. The pulse radar device as claimed in  claim 13 , also having an analog/digital converter which is configured to receive the intermediate frequency signal and to provide a digital signal which is configured to obtain an item of information relating to a period between an outputting of a pulse of the transmitter signal and a reception of an echo of the pulse as a receiver signal. 
     
     
       20. A method, comprising:
 receiving a first input signal and a second input signal, 
 switching a mixer on or off based on the first input signal, 
 mixing the first input signal and the second input signal in order to generate a mixer output signal, wherein a DC signal component of the mixer output signal depends on whether the mixer is switched on or off, 
 switching a downstream circuit on or off based on the DC signal component of the mixer output signal, and 
 providing an output signal based on the mixer output signal. 
 
     
     
       21. A radar method comprising:
 providing a pulsed transmitter signal and a pulsed local oscillator signal based on one or more oscillator signals, 
 outputting the pulsed transmitter signal at an antenna, 
 receiving a receiver signal, which is based on an echo of the pulsed transmitter signal, from an antenna, and 
 receiving the output signal using the method as claimed in  claim 20 , wherein the first input signal is based on the pulsed local oscillator signal and the second input signal is based on the receiver signal, and wherein the output signal constitutes an intermediate frequency signal of the pulsed local oscillator signal and the receiver signal.